diff --git a/modules/core/i18n.nix b/modules/core/i18n.nix
new file mode 100644
index 0000000..5bc69f8
--- /dev/null
+++ b/modules/core/i18n.nix
@@ -0,0 +1,7 @@
+{
+  i18n.defaultLocale = "en_US.UTF-8";
+  i18n.supportedLocales = [
+    "en_US.UTF-8/UTF-8"
+    "ja_JP.UTF-8/UTF-8"
+  ];
+}